A system, controller, and method for aligning a stereo camera of a vehicle mounted object detection system that includes a first camera and a second camera mounted spaced apart on a vehicle. An image from each camera at two different times is used to determine an observed displacement of an object relative to the vehicle. A predicted displacement of the object relative to the vehicle is also determined using either a difference of vehicle position measured based on other vehicle measurements or GPS, or a difference of size of the object in images taken at the two different times. Alignment is provided by determining a triangulation correction based on a difference of the observed displacement and the predicted displacement to correct for misalignment of the cameras.